The National Labor Relations Act (NLRA), which is enforced by the National Labor Relations Board (NLRB), protects employees who engage in “protected concerted activity.” That includes discussions regarding terms and conditions of employment.

The NLRA used to apply just to the company cafeteria, coffee station and the water cooler. But with Facebook, Twitter and blogs becoming the epicenter of workplace conversation, the NLRB’s new focus is employers’ social media policies that limit what workers can say online.

On April 22, an NLRB administrative law judge (ALJ) ruled that four provisions in Kroger’s online communications policy violated federal labor law because the provisions would “reasonably tend to chill employees in the exercise of their rights.”

One provision required employees to use a prescribed disclaimer if they identified themselves as Kroger employees and “publish(ed) any work related information online.” The disclaimer specified that the postings of the employee did not represent the opinions of Kroger.

The ALJ determined that the provision was “extremely burdensome” due to the number of communications it affected, including Facebook posts, comments on blogs and news articles, and even “likes.” While the ALJ recognized Kroger’s legitimate interest in employees not appearing to be the company’s spokesperson, he wrote that the “disclaimer rule is manifestly broader than its legitimate interest.”

Another provision the ALJ struck down was the restriction on the discussion of confidential and proprietary information. The rule prohibiting employees from commenting on “rumors, speculation or personnel matters” could be construed as prohibiting discussion of issues “at the heart” of protected activity including wages and other terms and conditions.

Similarly, the ALJ invalidated a provision prohibiting comments on rumors or speculation related to the company’s “business plans” since it encompassed subjects on which employees have a right to speak including transfers, potential shutdown, closures and layoffs. The ALJ distinguished this provision from a lawful provision proscribing “harmful gossip,” reasoning that Kroger’s provision prohibited discussion on specific topics that included protected subjects.

Kroger found out the hard way what other employers have learned before – even innocuous sounding social media policies may violate the NLRA. If you’ve been using a policy for a while, or if you’re thinking about adopting one, you’d better think through all the implications.